In a large bowl, mix together the softened butter and peanut butter. Then mix in the rice cereal, powdered sugar, and vanilla extract.
Roll into balls (I use a tablespoon-worth for each buckeye.) Place on a parchment-lined baking sheet and spear the top of each ball with a toothpick.
Chill in the freezer until hardened (about 20 minutes.)
Using the double boiler method, melt the chocolate chips.
While holding the toothpick, dip each buckeye in the melted chocolate until well-coated and let the excess drip off. To maintain the true "buckeye" appearance, leave a bare circle without chocoalte on top. Place back on the baking sheet and remove the toothpick.
Let the chocolate set in the fridge before eating or storing. Optional: To cover the toothpick hole smooth it over with a small spoon or your finger.